1. Field of the Invention
The invention relates to a method for producing an absorbent fiber product, according to which a parent fiber product that comprises fibers that, on the one hand, lie at a statistical distance from one another and, on the other hand, make contact with one another at contact points, is treated to have enhanced properties, such as greater absorbency and increased softness. The invention also relates to a corresponding absorbent fiber product produced in accordance with this method.
2. Background of the Invention
Fiber products such as hygiene products or so-called non-woven products like paper used for paper toweling, toilet paper and tissues etc. are very absorbent. The absorbency capability of a fiber product determines its quality and value. The prevailing types of fiber used are, for example, chemical wood pulp.
The absorbency capability of a fiber product is essentially determined by the unrestricted volume achieved by such a fiber product. In this connection, the arrangement of the fibers which, on the one hand, lie at a statistical distance from one another and, on the other hand, make contact with one another at contact points, is of importance. The interstitial space between the fibers can absorb liquids of all kinds. The absorbency capability of the fiber itself also plays a role.
Other well-known methods for the production of absorbent fiber products concentrate on producing a fiber product with absorbency capabilities that rely on the above mentioned arrangement of the fibers as well as the characteristics of the fibers themselves during the production process. Up until now, no additional means exist that can increase the absorbency capability of fiber products thus taking into consideration the specific characteristics of fiber products.
EP 0 671 504 A1 relates to a method for the production of foam material from waste paper and the like which as a liquid, preferably, watery pulp is heat treated as the pulp is exposed to microwave radiation so that the paper pulp is expanded from the resulting steam and is left in a porous state.
EP 0 989 231 A2 relates to a method for setting the moisture profile of a drying fiber web whereby the fact that water absorbs more high frequencies and/or microwaves than dry paper or its fibers do, is taken advantage of.
DE 196 39 491 C2 describes the enlargement of the surface of particles such as granulate or powder, for example, concrete fragments so that, at least to a limited extent, particles that absorb liquid are subjected to a liquid or its humid atmosphere until the liquid has penetrated at least into the surface area of the particle but preferably to the core. Subsequently, the liquid containing particles are radiated with microwaves until the penetrated liquid is rapidly evaporated and the particle structure bursts open. This method is mostly suitable for hard particle structures and the result of the method is burst particles as the liquid within the particle is evaporated.
As opposed to loose particles that lie next to each other, a fiber product consists of a conglomerate of fibers which because of their characteristics stick together and hold together the conglomerate as, for example, paper. On the one hand, the fibers lie at a statistical distance from one another and, on the other hand, make contact with one another at contact points.
The implementation of the above described method using fiber products of the type described above would render the fiber product unusable and would at the very least have detrimental drawbacks since the fiber structure and the conglomerate would be destroyed or burst in an uncontrolled manner. Furthermore, the intensive irradiation would thermally affect the fibers used in the fiber product and would thermally damage the fiber material which only appears to superficially increase absorbency. Lasting damage to the fiber would result in a rough paper product that would disintegrate easily when wet, which would render the fiber product less absorbent and virtually useless.
No production method is known that tries to advantageously influence the absorbency capabilities of fiber products after production. A production method that would largely eliminate the unwanted thermal damage to the fiber material but that also would significantly increase absorbency of an absorbent fiber product is needed.